The proposal is for the design and conduct of a double-blind, placebo-controlled trial to evaluate in normal infants, the safety and efficacy of two acellular pertussis vaccines prepared in Japan. The vaccines to be evaluated are J-NIH-6 a Biken Institute produced vaccine which contains both lymphocyte promoting factor, (LPF) and fimbrial hemagglutinin (FHA), and J-NIH-7 produced by the same Institute but containing only LPF in form toxoid. A total of 3,720 children will participate in a 13 center, double blind randomized controlled trial. Twenty-five percent of the study group will receive an alum precipitated placebo and 37 1/2 percent will each receive one of the two alum absorbed component vaccines. The final sample size is based on the following assumptions: (1) pertussis incidence of 4 percent in the controls during the 16 month follow-up period, (2) a protective efficacy of 90 percent, and null hypothesis that each vaccine efficacy is above 70 percent. The vaccine will be administered in two doses at 6 and 8 months of age. Sera will be drawn prior to the first dose and 8-12 weeks after the second dose. The study personnel will be blinded to whether vaccine or placebo is used in a particular child.